December in Klamath Falls is the snowiest and the coldest month of the year. In December, the weather in Klamath Falls is typically cold. Average daily high temperature in December is about 3 degrees above zero. On average, Klamath Falls has 11 cloudy, 7 sunny, 7 partly cloudy, 3 rainy, and 3 snowy days in December. The rains are usually heavy. December as well as January, February, March, and April is considered the most uncomfortable time to visit Klamath Falls.